title: E47 controls the developmental integrity and cell cycle quiescence of multipotential hematopoietic progenitors.
abstract: Little is known about the transcriptional regulators that control the proliferation of multipotent bone marrow progenitors. Understanding the mechanisms that restrict proliferation is of significant interest since the loss of cell cycle integrity can be associated with hematopoietic exhaustion, bone marrow failure, or even oncogenic transformation. Herein, we show that multipotent LSKs (lineage(-)Sca(high)c-kit(+)) from E47-deficient mice exhibit a striking hyperproliferation associated with a loss of cell cycle quiescence and increased susceptibility to in vivo challenge with a mitotoxic drug. Total LSKs contain long-term self-renewing hematopoietic stem cells and downstream multipotential progenitors (MPPs) that possess very limited or no self-renewal ability. Within total LSKs, we found specific developmental and functional deficits in the MPP subset. E47 knockout mice have grossly normal numbers of self-renewing hematopoietic stem cells but a 50-70% reduction in nonrenewing MPPs and downstream lineage-restricted populations. The residual MPPs in E47 knockout mice fail to fully up-regulate flk2 or initiate V(D)J recombination, hallmarks of normal lymphoid lineage progression. Consistent with the loss of normal cell cycle restraints, we show that E47-deficient LSKs have a 50% decrease in p21, a cell cycle inhibitor and known regulator of LSK proliferation. Moreover, enforced expression studies identify p21 as an E47 target gene in primary bone marrow LSKs. Thus, E47 appears to regulate the developmental and functional integrity of early hematopoietic subsets in part through effects on p21-mediated cell cycle quiescence.
authors.affiliation: Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Lela
authors.initials: L
authors.lastname: Kardava
authors.forename: Anthony
authors.initials: A
authors.lastname: St Leger
authors.forename: Kathleen
authors.initials: K
authors.lastname: Martincic
authors.forename: Barbara
authors.initials: B
authors.lastname: Varnum-Finney
authors.forename: Irwin D
authors.initials: ID
authors.lastname: Bernstein
authors.forename: Christine
authors.initials: C
authors.lastname: Milcarek
authors.forename: Lisa
authors.initials: L
authors.lastname: Borghesi
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000235:genetics / Q000276:immunology*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D019070:Cell Lineage / Q000235:genetics / Q000276:immunology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology; D018390:Gene Targeting; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D039902:Multipotent Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D016192:Resting Phase, Cell Cycle / Q000235:genetics / Q000276:immunology*; D051820:TCF Transcription Factors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D058125:Transcription Factor 7-Like 1 Protein; D014161:Transduction, Genetic
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D051820:TCF Transcription Factors; C544912:TCF7L1 protein, human; C544913:Tcf7l1 protein, mouse; D058125:Transcription Factor 7-Like 1 Protein